Folded waveguide phase shifters

ABSTRACT

In an embodiment, a phase shifter includes: a light input end; a light output end; a p-type semiconductor material, and an n-type semiconductor material contacting the p-type semiconductor material along a boundary area, wherein the boundary area is greater than a length from the light input end to the light output end multiplied by a core width of the phase shifter.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/952,602, filed Nov. 19, 2020, which is a continuation application ofU.S. patent application Ser. No. 16/532,270 filed Aug. 5, 2019, now U.S.Pat. No. 10,845,670, which claims priority to U.S. provisional patentapplication Ser. No. 62/719,558 filed on Aug. 17, 2018, each of whichare incorporated by reference herein.

BACKGROUND

Optical communications encode data by modulating a beam of light. Thismodulation may be, for example, upon the intensity or amplitude of thebeam of light. This type of amplitude modulation may be achieved bycombining a selectively delayed copy of a light beam with the light beamitself. For example, destructive interference may occur when the copy ofthe light beam is subjected to a phase delay of pi radians and combinedwith the original light beam itself. This destructive interference mayyield minimum output intensity. However, constructive interference mayoccur when the copy of the light beam is subjected to no phase delay.Constructive interference may yield a maximum output intensity.

Phase delay may be controlled and/or implemented by a phase shifter.Typical phase shifters include an n-type semiconductor materialcontacting a p-type semiconductor material along a boundary area that isequal to a length from a light input end to a light output endmultiplied by a width of the phase shifter. However, the effectivenessof such phase shifters may be limited by set parameters such as thewidth of the phase shifter and the length of the boundary from the lightinput end to the light output end. Therefore, traditional phase shiftersmay not be entirely satisfactory.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that various features are not necessarily drawn to scale. In fact,the dimensions and geometries of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIG. 1 is a block diagram of a modulator as part of a processing system,in accordance with some embodiments.

FIG. 2A is a block diagram of the modulator that utilizes a foldedwaveguide phase shifter, in accordance with some embodiments.

FIG. 2B is a diagram of the modulator illustrated as a Mach-Zehndermodulator that utilizes a folded waveguide phase shifter, in accordancewith some embodiments.

FIG. 2C is a block diagram of a ring modulator that utilizes a foldedwaveguide phase shifter in the shape of a ring, in accordance with someembodiments.

FIG. 3A illustrates a longitudinal cross sectional view of a light inputend and a light output end of a folded waveguide phase shifter, inaccordance with some embodiments.

FIG. 3B illustrates a longitudinal cross sectional view of a zig zagboundary area, in accordance with some embodiments.

FIG. 3C illustrates a lateral cross sectional view of the zig zagboundary area across line A-A of FIG. 3B, in accordance with someembodiments.

FIG. 3D illustrates an alternate lateral cross sectional view of the zigzag boundary area, in accordance with some embodiments.

FIG. 4A illustrates a longitudinal cross sectional view of a light inputend and a light output end of a folded waveguide phase shifter, inaccordance with some embodiment.

FIG. 4B illustrates a longitudinal cross sectional view of a circularboundary area, in accordance with some embodiments.

FIG. 4C illustrates a lateral cross sectional view of the circularboundary area that forms a cylinder across line B-B of FIG. 4B, inaccordance with some embodiments.

FIG. 4D illustrates a lateral cross sectional view of the circularboundary area that forms a sphere, in accordance with some embodiments.

FIG. 4E illustrates a lateral cross sectional view of the circularboundary area that forms an elliptical sphere, in accordance with someembodiments.

FIG. 5A illustrates a longitudinal cross sectional view of a light inputend and a light output end of a folded waveguide phase shifter, inaccordance with some embodiments.

FIG. 5B illustrates a longitudinal cross sectional view of amulti-pointed star boundary area, in accordance with some embodiment.

FIG. 5C illustrates a lateral cross sectional view of the multi-pointedstar boundary area that forms a multi-pointed star cylinder across lineC-C of FIG. 5B, in accordance with some embodiments.

FIG. 5D illustrates a lateral cross sectional view of the multi-pointedstar boundary area that forms a three dimensional multi-pointed star, inaccordance with some embodiments.

FIG. 6 is a flow chart of a folded waveguide phase shifter modulatorassembly process, in accordance with some embodiments.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following disclosure describes various exemplary embodiments forimplementing different features of the subject matter. Specific examplesof components and arrangements are described below to simplify thepresent disclosure. These are, of course, merely examples and are notintended to be limiting. For example, it will be understood that when anelement is referred to as being “connected to” or “coupled to” anotherelement, it may be directly connected to or coupled to the otherelement, or one or more intervening elements may be present.

In addition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Systems and methods in accordance with various embodiments are directedto a folded waveguide phase shifter with an increased boundary areabetween p-type semiconductor materials and n-type semiconductormaterials. This increased boundary area may be increased from merelyhaving the boundary area be equal to a length from a light input end toa light output end multiplied by a core width of a waveguide phaseshifter. Accordingly, the boundary area may be increased by including apattern or fold to effectuate an increased boundary area. Stated anotherway, the boundary area may include at least one fold or nonlineartransition and not be present in only a straight line to effectuate anincreased boundary area.

For example, the boundary area may be increased by adopting various twodimensional and/or three dimensional folds that make patterns for theboundary area. These patterns may include, for example, diagonals,triangles, arcs, circles, spheres, rectangles (e.g., blocks), squares,cylinders, and/or any other type of pattern that may be adopted toincrease the boundary area between the n-type semiconductor material andthe p-type semiconductor material. In particular embodiments, thesepatterns may form discrete shapes, such as circles or multi-pointedstars, from a light input end to a light output end of the waveguide.

In certain embodiments, the following equation may be utilized toexpress the relationship between a phase shift φ and an effectiverefractive index Δn in a waveguide:

φ=(2π/λ)ΔnL

where λ is the optical wavelength and L is the interaction length or thelength of the waveguide from the light input end to the light outputend. Also, the effective refractive index Δn is directly related to thesize of the boundary area between a p-type semiconductor material an-type semiconductor material. Therefore, the amount of phase shift φmay be directly related to the size of the boundary area between ap-type semiconductor material a n-type semiconductor material within awaveguide. This means that as the boundary area is increased, the amountof phase shift may also be increased for the same interaction length L(e.g., length of the waveguide from the light input end to the lightoutput end). Accordingly, an increased boundary area for a foldedwaveguide phase shifter may also increase the amount of phase shift φwithout requiring additional length for the folded waveguide phaseshifter.

In certain embodiments, the doping concentration for the p-typesemiconductor material and the n-type semiconductor material may besubstantially the same. In other embodiments, the doping of the p-typesemiconductor material may be more than that of the n-type semiconductormaterial. For example, the doping of the p-type semiconductor materialmay be from about 2 to about 100 times more than that of the n-typesemiconductor material. In yet other embodiments, the doping of then-type semiconductor material may be more than that of the p-typesemiconductor material. For example, the doping of the n-typesemiconductor material may be from about 2 to about 100 times more thanthat of the p-type semiconductor material. In particular embodiments,the phase shifter may be implemented with a wave guide, such as with aMach-Zehnder modulator and/or a ring modulator. In particularembodiments, the range of concentrations of P and N doping may bebetween about 1×10¹⁶ atoms/cm³ to about 1×10²¹ atoms/cm³. For example,in certain embodiments, the range of concentration of P and N doping maybe about 1×10⁷ atoms/cm³ to about 1×10¹⁸ atoms/cm³. In certainembodiments, the P and N junctions may be side by side (e.g., adjacent).However, in other embodiments, the P and N junctions may be separated byabout 10 nanometers to about 100 nanometers.

In further embodiments, a folded waveguide phase shifter may be fromabout 250 nanometers to about 2 micrometers in core width, from about100 nanometers to about 500 nanometers in core height, and a variablelength from a light input end to a light output end. For example, afolded waveguide phase shifter in certain embodiments may be from about300 nanometers to about 500 nanometers in core width and from about 200nanometers to about 300 nanometers in core height.

In various embodiments, a folded waveguide phase shifter may have a corethat is built from a semiconductor material, such as a Group IV materialsuch as silicon (Si) or germanium (Ge). In further embodiments, a foldedwaveguide phase shifter may have a core that is built from a Group III-Vmaterial such as like gallium arsenide (GaAs) or indium phosphide (InP).Cladding for a folded waveguide phase shifter may include dielectricmaterials such as silicon oxide (SiOx), germanium oxide (GeOx), siliconnitride (SiNx), or silicon-oxynitride (SiON). In certain embodiments,the effective index of cladding may be less than the effective index ofthe core.

FIG. 1 is a block diagram of a modulator 102 as part of a processingsystem 104, in accordance with some embodiments. More specifically, FIG.1 illustrates how an optical source 106 may transmit a light beam to themodulator 102 with which the light beam 107 is modulated and received bythe receiver 108. Each component (e.g., optical source 106, modulator102, and receiver 108) may be connected by an optical fiber or opticalconduit 110. In certain embodiments, the optical source 106 may be alaser and the light beam 107 a laser beam. In particular embodiments,the optical conduits 110 may include for example optical fibers, opticalwaveguides, free space or other suitable optical conduits.

The processing system 104 may be part of the internal components of acomputer system. For example, the processing system 104 may be part of,for example, a personal or laptop computer, with the modulator 102included in a processor of the processing system 104 and receiver 108included in, for example, an internal card of the processing system 104,such as for example a video controller card, a network interface card,memory or the like. In another embodiment, the processing system 104 maybe included in a single chip or chipset with the optical source 106 andreceiver 108 being internal components of the chip or chipset. Inanother embodiment, the processing system 104 may be included in acommunications network with optical source 106 and receiver 108 beingincluded in separate components of the communications network.

As will be discussed in further detail below, the modulator 102 mayinclude a folded waveguide phase shifter with an increased boundary areabetween p-type semiconductor materials and n-type semiconductormaterials. For example, the boundary area may be increased by adoptingvarious two dimensional and/or three dimensional folds that makepatterns for the boundary. These patterns may include, for example,diagonals, triangles, arcs, rectangles (e.g., blocks), squares, circles,spheres, cylinders, and/or any other type of pattern that may be adoptedto increase the boundary area between the n-type semiconductor materialand the p-type semiconductor material. In particular embodiments, thesepatterns may form discrete shapes from a light input end to a lightoutput end of the waveguide.

FIG. 2A is a block diagram of the modulator 102 that utilizes a foldedwaveguide phase shifter 202, in accordance with some embodiments. Themodulator 102 may include least one of two arms optically coupledbetween cascaded Y-branch couplers 206 disposed in semiconductormaterial. In operation, the light beam 107 is split such that a firstportion of the light beam 107 is directed through one of the arms of thecascaded Y-branch couplers 206 and a second portion of light beam 107 isdirected through the other one of the arms of the cascaded Y-branchcouplers 206. One of the arms of the cascaded Y-branch couplers 206includes the folded waveguide phase shifter 202, which performs a phaseshift. The first and second portions of the light beam 107 are thenmerged such that the light beam 107 is modulated at the output 208 as aresult of constructive or destructive interference.

In one embodiment, only one of the arms of the cascaded Y-branchcouplers 206 includes the folded waveguide phase shifter 202. In anotherembodiment, both of the arms of the cascaded Y-branch couplers 206 mayinclude different the folded waveguide phase shifters, such as differentfolded waveguide phase shifters with different boundary areas. Forexample, one of the arms of the cascaded Y-branch couplers 206 includesthe folded waveguide phase shifter 202 with the other arm includinganother folded waveguide phase shifter 204.

FIG. 2B is a diagram of the modulator 102 illustrated as a Mach-Zehndermodulator that utilizes a folded waveguide phase shifter, in accordancewith some embodiments. The modulator 102 may include least one of twoarms optically coupled between cascaded Y-branch couplers 206 disposedin semiconductor material. In operation, the light beam 107 is splitsuch that a first portion of the light beam 107 is directed through afirst arm 210A of the cascaded Y-branch couplers 206 and a secondportion of light beam 107 is directed through a second arm 210B of thecascaded Y-branch couplers 206. Both of the first arm 210A, and secondarm 210B include the folded waveguide phase shifter 202, which performsa phase shift. However, the first arm 210A may longer than the secondarm 210B. The first and second portions of the light beam 107 are thenmerged such that the light beam 107 is modulated at the output 208 as aresult of constructive or destructive interference.

FIG. 2C is a block diagram of a ring modulator 220 that utilizes afolded waveguide phase shifter 222 in the shape of a ring, in accordancewith some embodiments. Stated another way, the ring modulator 220 mayimplement the folded waveguide phase shifter 222 in the shape of a ring.The ring modulator 220 may include, for example, two waveguides 224A,224B which may each receive a respective light beam 107. The light beammay transition from each respective waveguide 224A, 224B into and fromthe folded waveguide phase shifter 222 in the shape of a ring as anevanescent wave. The portions of the light beam in each respectivewaveguide 224A, 224B may be merged with the portions of the light beamthat propagated through the folded waveguide phase shifter 222 to bemodulated at the respective outputs 226A, 226B as a result ofconstructive or destructive interference. The operation of the ringmodulator 220 may be implemented in a conventional manner aside from theutilization of the folded waveguide phase shifter 222. Therefore,further discussion of the operation of the ring modulator 220 will notbe discussed herein for brevity.

FIG. 3A illustrates a longitudinal cross sectional view of a light inputend 304 and a light output end 306 of a folded waveguide phase shifter308, in accordance with some embodiments. The longitudinal crosssectional view, as a longitudinal cross section, may span from the lightinput end 304 to the light output end 306. The folded waveguide phaseshifter 308 may include a core 310 and a cladding 312. The core 310 maybe the part of the folded waveguide phase shifter 308 in which light maypropagate through from the light input end 304 to the light output end306. In certain embodiments, the core portion may be made of siliconwhile the cladding portion may be made of silicon oxide. However, thecore portion and the cladding portion may be made of other materials asdesired for different applications, in various embodiments. For example,the core portion may be made from a semiconductor material, such as aGroup IV material such as silicon (Si) or germanium (Ge) and/or a GroupIII-V material such as like gallium arsenide (GaAs) or indium phosphide(InP). The cladding portion may include dielectric materials such assilicon oxide (SiOx), germanium oxide (GeOx), silicon nitride (SiNx), orsilicon-oxynitride (SiON). In certain embodiments, the effective indexof cladding may be less than the effective index of the core.

FIG. 3B illustrates a longitudinal cross sectional view of a zig zagboundary area 320, in accordance with some embodiments. The boundaryarea 320 may be between a first type of semiconductor material 322A anda second type of semiconductor material 322B. In certain embodiments,the first type of semiconductor material 322A may be a p-typesemiconductor material while the second type of semiconductor material322B may be an n-type semiconductor material. However, in otherembodiments, the first type of semiconductor material 322A may be ann-type semiconductor material while the second type of semiconductormaterial 322B may be a p-type semiconductor material.

The zig zag boundary area 320 may be greater than a length of the foldedwaveguide phase shifter 308 along an extension axis 326A (e.g., an axisalong which the light substantially propagates from a light input end toa light output end) multiplied by a core width of the core 310 along anypossible perpendicular axes (e.g., an axis perpendicular to theextension axis that may be combined with the extension axis to form anarea). In certain embodiments with two core widths along respectiveaxes, one of the core widths along one axis perpendicular to theextension axis may be referred to as a core width while the other of thecore widths along another axis perpendicular to the extension axis maybe referred to as a core height. The extension axis may also bereferenced as a Z axis. When the core 310 of the folded waveguide phaseshifter 308 is in the shape of a rectangular bar, the perpendicular axismay be broken up into a first perpendicular axis 326B (e.g., referencedas an X axis) and a second perpendicular axis (e.g., referenced as a Yaxis). When the core 310 of the folded waveguide phase shifter 308 is inthe shape of a cylinder, the perpendicular axis or may be along adiameter perpendicular to the extension axis 326A.

For example, the zig zag boundary area 320 may extend fully along theextension axis 326A and extend fully several times along the secondperpendicular axis 326C within the core 310, thus forming a zigzag line.This zigzag line would be longer than the core 310 of the foldedwaveguide phase shifter 308 along the length of the extension axis.Also, the zig zag boundary area 320 may extend clear across the core 310along a core width from one side of the core 310 to another side of thecore 310. Accordingly, at least for a same core width along any possibleperpendicular axes, the zig zag boundary area 320 that at least extendsalong the zig zag line would be greater than a length of the foldedwaveguide phase shifter 308 along the extension axis 326A (e.g., as astraight line) multiplied by a core width along any perpendicular axes(e.g., as a straight line).

FIG. 3C illustrates a lateral cross sectional view 350 of the zig zagboundary area across line A-A of FIG. 3B, in accordance with someembodiments. The lateral cross sectional view 350 may be of a crosssection that would not include the light input end and/or the lightoutput end. Stated another way, the lateral cross sectional view 350 maybe a view perpendicular to a longitudinal cross sectional view. As notedabove, the zig zag boundary area 320 may be greater than a length of thefolded waveguide phase shifter 308 along the extension axis multipliedby a core width of the core 310 along any possible perpendicular axes.The possible perpendicular axes may include the first perpendicular axis326B (e.g., referenced as an X axis) and a second perpendicular axis326C (e.g., referenced as a Y axis). In certain embodiments with twocore widths along respective axes, one of the core widths along one axisperpendicular to the extension axis may be referred to as a core widthwhile the other of the core widths along another axis perpendicular tothe extension axis may be referred to as a core height. Also, the zigzag boundary area 320 may extend fully along the extension axis andextend fully along the second perpendicular axis 326C within the core310, thus forming a zig zag line. Accordingly, the zig zag boundary area320 would be greater than a length of the folded waveguide phase shifter308 along the extension axis 326A (e.g., as a straight line) multipliedby a core width along any perpendicular axes (e.g., as a straight line).

FIG. 3D illustrates an alternate lateral cross sectional view 350A ofthe zig zag boundary area, in accordance with some embodiments. Thealternate lateral cross sectional view 350A illustrates an alternatecross sectional structure (e.g., in a cross sectional view) relative tothe cross sectional structure in the cross sectional view 350 of FIG.3C. Returning to FIG. 3D, for example, the alternate lateral crosssectional view 350A may be of a cross section that would not include thelight input end and/or the light output end. Stated another way, thealternate lateral cross sectional view 350A may be a view perpendicularto a longitudinal cross sectional view. As noted above, the zig zagboundary area 320 may be greater than a length of the folded waveguidephase shifter 308 along the extension axis multiplied by a core width ofthe core 310 along any possible perpendicular axes. The possibleperpendicular axes may include the first perpendicular axis 326B (e.g.,referenced as an X axis) and a second perpendicular axis 326C (e.g.,referenced as a Y axis). In certain embodiments with two core widthsalong respective axes, one of the core widths along one axisperpendicular to the extension axis may be referred to as a core widthwhile the other of the core widths along another axis perpendicular tothe extension axis may be referred to as a core height. Also, the zigzag boundary area 320 may extend fully along the extension axis andextend fully along the second perpendicular axis 326C within the core310, thus forming a zig zag line. More specifically, the zig zagboundary area 320 may extend across a diagonal or hypotenuse formed withthe first perpendicular axis 326B and the second perpendicular axis326C. This hypotenuse may be longer than a core width of the core 310along any of the first perpendicular axis 326B and the secondperpendicular axis 326C. Accordingly, the zig zag boundary area 320would be greater than a length of the folded waveguide phase shifter 308along the extension axis 326A (e.g., as a straight line) multiplied by acore width along any perpendicular axes (e.g., as a straight line).

FIG. 4A illustrates a longitudinal cross sectional view of a light inputend 404 and a light output end 406 of a folded waveguide phase shifter408, in accordance with some embodiment. The longitudinal crosssectional view of a longitudinal cross section may span from the lightinput end 404 to the light output end 406. The folded waveguide phaseshifter 408 may include a core 410 and a cladding 412. The core 410 maybe the part of the folded waveguide phase shifter 408 in which light maypropagate through from the light input end 404 to the light output end406.

FIG. 4B illustrates a longitudinal cross sectional view of a circularboundary area 420, in accordance with some embodiments. The circularboundary area 420 may be between a first type of semiconductor material422A and a second type of semiconductor material 422B. In certainembodiments, the first type of semiconductor material 422A may be ap-type semiconductor material while the second type of semiconductormaterial 422B may be an n-type semiconductor material. However, in otherembodiments, the first type of semiconductor material 422A may be ann-type semiconductor material while the second type of semiconductormaterial 422B may be a p-type semiconductor material.

The circular boundary area 420 may be greater than a length of thefolded waveguide phase shifter 408 along an extension axis 426A (e.g.,an axis along which the light substantially propagates from a lightinput end to a light output end) multiplied by a core width of the core410 along any possible perpendicular axes (e.g., an axis perpendicularto the extension axis that may be combined with the extension axis toform an area). The extension axis may also be referenced as a Z axis. Incertain embodiments with two core widths along respective axes, one ofthe core widths along one axis perpendicular to the extension axis maybe referred to as a core width while the other of the core widths alonganother axis perpendicular to the extension axis may be referred to as acore height. When the core 410 of the folded waveguide phase shifter 408is in the shape of a rectangular bar, the perpendicular axis may bebroken up into a first perpendicular axis 426B (e.g., referenced as an Xaxis) and a second perpendicular axis (e.g., referenced as a Y axis).When the core 410 of the folded waveguide phase shifter 408 is in theshape of a cylinder, the perpendicular axis or may be along a diameterperpendicular to the extension axis 426A.

The circular boundary area 420 may be increased by adopting variousfolds or patterns of discrete shapes for the boundary from the lightinput end 404 to the light output end 406 of the folded waveguide phaseshifter 408. For example, the circular boundary area 420 may propagatewith discrete circular shapes along the extension axis 426A. Thecircular boundary area 420, as discrete circumferences of respectivediscrete circles, may be of a dimension to have a greater length than alength of a line from the light input end 404 to the light output end406 of the core 410 along the extension axis 426A. Accordingly, for asame core width along any possible perpendicular axes, the circularboundary area 420 may be greater than a length of the folded waveguidephase shifter 408 along the extension axis 426A (e.g., as a straightline) multiplied by a core width along any possible perpendicular axes(e.g., as a straight line).

FIG. 4C illustrates a lateral cross sectional view 430 of the circularboundary area that forms a cylinder 432 across line B-B of FIG. 4B, inaccordance with some embodiments. The lateral cross sectional view 430may be of a cross section that would not include the light input endand/or the light output end. Stated another way, the lateral crosssectional view may be a view perpendicular to a longitudinal crosssectional view. The circular boundary area that forms a cylinder 432 maybe greater than a length of the folded waveguide phase shifter 408 alongthe extension axis multiplied by a core width of the core 410 along anypossible perpendicular axes. In certain embodiments with two core widthsalong respective axes, one of the core widths along one axisperpendicular to the extension axis may be referred to as a core widthwhile the other of the core widths along another axis perpendicular tothe extension axis may be referred to as a core height. The possibleperpendicular axes may include the first perpendicular axis 426B (e.g.,referenced as an X axis) and a second perpendicular axis 426C (e.g.,referenced as a Y axis).

The circular boundary area that forms a cylinder 432 may extend fullyalong the second perpendicular axis 426C within the core 410. Statedanother way, the circular boundary area that is shaped with discretecircular shapes in the longitudinal cross sectional view as illustratedin FIG. 4B, and that extends fully along the second perpendicular axisin the lateral cross sectional view 430 of FIG. 4C would form thecircular boundary area that forms a cylinder 432 when visualized inthree dimensional space.

FIG. 4D illustrates a lateral cross sectional view 460 of the circularboundary area that forms a sphere 462, in accordance with someembodiments. The circular boundary area that forms a sphere 462 may begreater than a length of the folded waveguide phase shifter 408 alongthe extension axis multiplied by a core width of the core 410 along anypossible perpendicular axes. In certain embodiments with two core widthsalong respective axes, one of the core widths along one axisperpendicular to the extension axis may be referred to as a core widthwhile the other of the core widths along another axis perpendicular tothe extension axis may be referred to as a core height. The possibleperpendicular axes may include the first perpendicular axis 426B (e.g.,referenced as an X axis) and a second perpendicular axis 426C (e.g.,referenced as a Y axis).

The circular boundary area that forms a sphere 462 may be a circle inthe lateral cross sectional view 460 within the core 410. Stated anotherway, the circular boundary area that is shaped with discrete circularshapes in the longitudinal cross sectional view as illustrated in FIG.4B, and that forms a circle in the lateral cross sectional view 460 ofFIG. 4D would form the circular boundary area that forms a sphere 462when visualized in three dimensional space.

FIG. 4E illustrates a lateral cross sectional view 480 of the circularboundary area that forms an elliptical sphere 482, in accordance withsome embodiments. The circular boundary area that forms an ellipticalsphere 482 may be greater than a length of the folded waveguide phaseshifter 408 along the extension axis multiplied by a core width of thecore 410 along any possible perpendicular axes. In certain embodimentswith two core widths along respective axes, one of the core widths alongone axis perpendicular to the extension axis may be referred to as acore width while the other of the core widths along another axisperpendicular to the extension axis may be referred to as a core height.The possible perpendicular axes may include the first perpendicular axis426B (e.g., referenced as an X axis) and a second perpendicular axis426C (e.g., referenced as a Y axis).

The circular boundary area that forms an elliptical sphere 482 may be anellipse in the lateral cross sectional view 480 within the core 410.Stated another way, the circular boundary area that is shaped withdiscrete circular shapes in the longitudinal cross sectional view asillustrated in FIG. 4B, and that forms an ellipse in the lateral crosssectional view 480 of FIG. 4E would form the circular boundary area thatforms an elliptical sphere 482 when visualized in three dimensionalspace.

FIG. 5A illustrates a longitudinal cross sectional view of a light inputend 504 and a light output end 506 of a folded waveguide phase shifter508, in accordance with some embodiments. The longitudinal crosssectional view may span a longitudinal cross section from the lightinput end 504 to the light output end 506. The folded waveguide phaseshifter 508 may include a core 510 and a cladding 512. The core 510 maybe the part of the folded waveguide phase shifter 508 in which light maypropagate through from the light input end 504 to the light output end506.

FIG. 5B illustrates a longitudinal cross sectional view of amulti-pointed star boundary area 520, in accordance with someembodiment. The multi-pointed star boundary area 520 may be between afirst type of semiconductor material 522A and a second type ofsemiconductor material 522B. In certain embodiments, the first type ofsemiconductor material 522A may be a p-type semiconductor material whilethe second type of semiconductor material 522B may be an n-typesemiconductor material. However, in other embodiments, the first type ofsemiconductor material 522A may be an n-type semiconductor materialwhile the second type of semiconductor material 522B may be a p-typesemiconductor material.

The multi-pointed star boundary area 520 may be greater than a length ofthe folded waveguide phase shifter 508 along an extension axis 526A(e.g., an axis along which the light substantially propagates from alight input end to a light output end) multiplied by a core width of thecore 510 along any possible perpendicular axes (e.g., an axisperpendicular to the extension axis that may be combined with theextension axis to form an area). The extension axis may also bereferenced as a Z axis. In certain embodiments with two core widthsalong respective axes, one of the core widths along one axisperpendicular to the extension axis may be referred to as a core widthwhile the other of the core widths along another axis perpendicular tothe extension axis may be referred to as a core height. When the core510 of the folded waveguide phase shifter 508 is in the shape of arectangular bar, the perpendicular axis may be broken up into a firstperpendicular axis 526B (e.g., referenced as an X axis) and a secondperpendicular axis (e.g., referenced as a Y axis). When the core 510 ofthe folded waveguide phase shifter 508 is in the shape of a cylinder,the perpendicular axis or may be along a diameter perpendicular to theextension axis 526A.

The multi-pointed star boundary area 520 may be increased by adoptingvarious folds or patterns of discrete shapes for the boundary from thelight input end 504 to the light output end 506 of the folded waveguidephase shifter 508. For example, the multi-pointed star boundary area 520may propagate with discrete multi-pointed star shapes along theextension axis 526A. The multi-pointed star boundary area 520, asdiscrete perimeters of respective discrete multi-pointed stars, may beof a dimension to have a greater length than a length of a line from thelight input end 504 to the light output end 506 of the core 510 alongthe extension axis 526A. Accordingly, for a same core width along anypossible perpendicular axes, the multi-pointed star boundary area 520may be greater than a length of the folded waveguide phase shifter 508along the extension axis 526A (e.g., as a straight line) multiplied by acore width along any possible perpendicular axes (e.g., as a straightline).

FIG. 5C illustrates a lateral cross sectional view 530 of themulti-pointed star boundary area that forms a multi-pointed starcylinder 532 across line C-C of FIG. 5B, in accordance with someembodiments. The multi-pointed star boundary area that forms amulti-pointed star cylinder 532 may have more than three faces (e.g.,flat surfaces). The lateral cross sectional view 530 may be of a crosssection that would not include the light input end and/or the lightoutput end. Stated another way, the lateral cross sectional view may bea view perpendicular to a longitudinal cross sectional view. Themulti-pointed star boundary area that forms a multi-pointed starcylinder 532 may be greater than a length of the folded waveguide phaseshifter 508 along the extension axis multiplied by a core width of thecore 510 along any possible perpendicular axes. In certain embodimentswith two core widths along respective axes, one of the core widths alongone axis perpendicular to the extension axis may be referred to as acore width while the other of the core widths along another axisperpendicular to the extension axis may be referred to as a core height.The possible perpendicular axes may include the first perpendicular axis526B (e.g., referenced as an X axis) and a second perpendicular axis526C (e.g., referenced as a Y axis).

The multi-pointed star boundary area that forms a multi-pointed starcylinder 532 may extend fully along the second perpendicular axis 526Cwithin the core 510. Stated another way, the multi-pointed star boundaryarea that is shaped with discrete multi-pointed star shapes in thelongitudinal cross sectional view as illustrated in FIG. 5B, and thatextends fully along the second perpendicular axis in the lateral crosssectional view 530 of FIG. 5C would form the multi-pointed star boundaryarea that forms a multi-pointed star cylinder 532 when visualized inthree dimensional space.

FIG. 5D illustrates a lateral cross sectional view 560 of themulti-pointed star boundary area that forms a three dimensionalmulti-pointed star 562, in accordance with some embodiments. The lateralcross sectional view 560 may be of a cross section that would notinclude the light input end and/or the light output end. Stated anotherway, the lateral cross sectional view may be a view perpendicular to alongitudinal cross sectional view. The multi-pointed star boundary areathat forms a three dimensional multi-pointed star 562 may be greaterthan a length of the folded waveguide phase shifter 508 along theextension axis multiplied by a core width of the core 510 along anypossible perpendicular axes. In certain embodiments with two core widthsalong respective axes, one of the core widths along one axisperpendicular to the extension axis may be referred to as a core widthwhile the other of the core widths along another axis perpendicular tothe extension axis may be referred to as a core height. The possibleperpendicular axes may include the first perpendicular axis 526B (e.g.,referenced as an X axis) and a second perpendicular axis 526C (e.g.,referenced as a Y axis).

The multi-pointed star boundary area that forms a three dimensionalmulti-pointed star 562 may be a multi-pointed star in the lateral crosssectional view 560 within the core 510. Stated another way, themulti-pointed star boundary area that is shaped with discretemulti-pointed star shapes in the longitudinal cross sectional view asillustrated in FIG. 5B, and that forms a multi-pointed star in thelateral cross sectional view 560 of FIG. 5D would form the multi-pointedstar boundary area that forms a three dimensional multi-pointed star 562when visualized in three dimensional space.

FIG. 6 is a flow chart of a folded waveguide phase shifter modulatorassembly process 600, in accordance with some embodiments. It is notedthat the process 600 is merely an example, and is not intended to limitthe present disclosure. Accordingly, it is understood that additionaloperations may be provided before, during, and after the process 600 ofFIG. 6, certain operations may be omitted, certain operations may beperformed concurrently with other operations, and that some otheroperations may only be briefly described herein.

At operation 602, a folded waveguide phase shifter may be formed. Asnoted above, a folded waveguide phase shifter may have an increasedboundary area between p-type semiconductor materials and n-typesemiconductor materials. This increased boundary area may be increasedfrom merely having the boundary area be equal to a length from a lightinput end to a light output end multiplied by a core width of awaveguide phase shifter. Accordingly, the increased boundary may befolded in that the boundary is not present in only a straight line butincludes at least one fold or nonlinear transition. For example, theboundary area may be increased by adopting various two dimensionaland/or three dimensional folds that make patterns for the boundary.These patterns may include, for example, diagonals, triangles, arcs,circles, rectangles (e.g., blocks), squares, spheres, cylinders, and/orany other type of pattern that may be adopted to increase the boundaryarea between the n-type semiconductor material and the p-typesemiconductor material. In particular embodiments, these patterns mayform discrete shapes from a light input end to a light output end of thewaveguide.

At operation 604, the folded waveguide phase shifter may be connectedwith components of a modulator. As noted above, a modulator may cause alight beam to be split such that a first portion of the light beam isdirected through one arm of the modulator and a second portion of lightbeam is directed through another arm of the modulator. At least one ofthe arms of the modulator may include (e.g., be connected with) thefolded waveguide phase shifter, which performs a phase shift.

In one embodiment, only one of the arms of the modulator includes thefolded waveguide phase shifter. In another embodiment, both of the armsof the modulator may include different folded waveguide phase shifters,such as different folded waveguide phase shifters with different typesof boundary areas or a same type of boundary area but that extends fordifferent lengths.

At operation 606, light output from the waveguides of the modulator,including the folded waveguide phase shifter, may be combined. Forexample, the first and second portions of the light beam mentioned inoperation 604 are merged such that the light beam is modulated at theoutput of the modulator as a result of constructive or destructiveinterference.

In an embodiment, a phase shifter includes: a light input end; a lightoutput end; a p-type semiconductor material, and an n-type semiconductormaterial contacting the p-type semiconductor material along a boundaryarea, wherein the boundary area is greater than a length from the lightinput end to the light output end multiplied by a core width of thephase shifter. In an embodiment, the boundary area zig zags from thelight input end to the light output end. In another embodiment, theboundary area extends from one end of the core width of the phaseshifter to a second end of the core width of the phase shifter. Inanother embodiment, the phase shifter comprises a core heightperpendicular to the core width of the phase shifter, where the boundaryarea extends from one end of the core height of the phase shifter to asecond end of the core height of the phase shifter. In anotherembodiment, the boundary area extends from one end of the core width ofthe phase shifter to a second end of the core width of the phaseshifter. In another embodiment, the boundary area forms discrete shapesfrom the light input end to the light output end. In another embodiment,the discrete shapes are spheres. In another embodiment, the discreteshapes are cylinders.

In an embodiment, a modulator includes: a first waveguide; and a secondwaveguide, comprising: a light input end, a light output end, a p-typesemiconductor material, and an n-type semiconductor material contactingthe p-type semiconductor material along a boundary area, wherein theboundary area is greater than a length from the light input end to thelight output end multiplied by a core width of the second waveguide,wherein the first waveguide is different than the second waveguide,wherein a first light output of the first waveguide is combined with asecond light output from the light output end. In another embodiment,the boundary area forms cylinders with more than 3 faces (e.g., flatsurfaces) from the light input end to the light output end. In anotherembodiment, the boundary area forms rectangular blocks from the lightinput end to the light output end. In another embodiment, the lightoutput end is coupled with a memory. In another embodiment, the firstwaveguide and the second waveguide are part of a processor. In anotherembodiment, the boundary area forms multi-pointed stars from the lightinput end to the light output end.

In an embodiment, a method includes: connecting a first waveguide with asecond waveguide different than the first waveguide, wherein the secondwaveguide comprises: a light input end, a light output end, a p-typesemiconductor material, and an n-type semiconductor material contactingthe p-type semiconductor material along a boundary area, wherein theboundary area is greater than a length from the light input end to thelight output end multiplied by a core width of the second waveguide,wherein the first waveguide is different than the second waveguide; andcombining a first light output of the first waveguide with a secondlight output from the light output end. Another embodiment includesconnecting an input light source to the light input end. Anotherembodiment includes connecting the light input end to a first waveguidelight input end. Another embodiment includes forming the boundary areawith a zig zag from the light input end to the light output end. Anotherembodiment includes forming the boundary area with discrete shapes fromthe light input end to the light output end. Another embodiment includesforming the boundary area from one end of the core width of the secondwaveguide to a second end of the core width of the second waveguide.

The foregoing outlines features of several embodiments so that thoseordinary skilled in the art may better understand the aspects of thepresent disclosure. Those skilled in the art should appreciate that theymay readily use the present disclosure as a basis for designing ormodifying other processes and structures for carrying out the samepurposes and/or achieving the same advantages of the embodimentsintroduced herein. Those skilled in the art should also realize thatsuch equivalent constructions do not depart from the spirit and scope ofthe present disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

In this document, the term “module” as used herein, refers to software,firmware, hardware, and any combination of these elements for performingthe associated functions described herein. Additionally, for purpose ofdiscussion, the various modules are described as discrete modules;however, as would be apparent to one of ordinary skill in the art, twoor more modules may be combined to form a single module that performsthe associated functions according embodiments of the invention.

A person of ordinary skill in the art would further appreciate that anyof the various illustrative logical blocks, modules, processors, means,circuits, methods and functions described in connection with the aspectsdisclosed herein can be implemented by electronic hardware (e.g., adigital implementation, an analog implementation, or a combination ofthe two), firmware, various forms of program or design codeincorporating instructions (which can be referred to herein, forconvenience, as “software” or a “software module), or any combination ofthese techniques. To clearly illustrate this interchangeability ofhardware, firmware and software, various illustrative components,blocks, modules, circuits, and steps have been described above generallyin terms of their functionality. Whether such functionality isimplemented as hardware, firmware or software, or a combination of thesetechniques, depends upon the particular application and designconstraints imposed on the overall system. Skilled artisans canimplement the described functionality in various ways for eachparticular application, but such implementation decisions do not cause adeparture from the scope of the present disclosure.

Furthermore, a person of ordinary skill in the art would understand thatvarious illustrative logical blocks, modules, devices, components andcircuits described herein can be implemented within or performed by anintegrated circuit (IC) that can include a general purpose processor, adigital signal processor (DSP), an application specific integratedcircuit (ASIC), a field programmable gate array (FPGA) or otherprogrammable logic device, or any combination thereof. The logicalblocks, modules, and circuits can further include antennas and/ortransceivers to communicate with various components within the networkor within the device. A general purpose processor can be amicroprocessor, but in the alternative, the processor can be anyconventional processor, controller, or state machine. A processor canalso be implemented as a combination of computing devices, e.g., acombination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other suitable configuration to perform the functionsdescribed herein.

Conditional language such as, among others, “can,” “could,” “might” or“may,” unless specifically stated otherwise, are otherwise understoodwithin the context as used in general to convey that certain embodimentsinclude, while other embodiments do not include, certain features,elements and/or steps. Thus, such conditional language is not generallyintended to imply that features, elements and/or steps are in any wayrequired for one or more embodiments or that one or more embodimentsnecessarily include logic for deciding, with or without user input orprompting, whether these features, elements and/or steps are included orare to be performed in any particular embodiment.

Additionally, persons of skill in the art would be enabled to configurefunctional entities to perform the operations described herein afterreading the present disclosure. The term “configured” as used hereinwith respect to a specified operation or function refers to a system,device, component, circuit, structure, machine, etc. that is physicallyor virtually constructed, programmed and/or arranged to perform thespecified operation or function.

Disjunctive language such as the phrase “at least one of X, Y, or Z,”unless specifically stated otherwise, is otherwise understood with thecontext as used in general to present that an item, term, etc., may beeither X, Y, or Z, or any combination thereof (e.g., X, Y, and/or Z).Thus, such disjunctive language is not generally intended to, and shouldnot, imply that certain embodiments require at least one of X, at leastone of Y, or at least one of Z to each be present.

It should be emphasized that many variations and modifications may bemade to the above-described embodiments, the elements of which are to beunderstood as being among other acceptable examples. All suchmodifications and variations are intended to be included herein withinthe scope of this disclosure and protected by the following claims.

What is claimed is:
 1. A phase shifter, comprising: a light input end; alight output end; a first semiconductor material, and a secondsemiconductor material different from the first semiconductor material,the second semiconductor material contacting the first semiconductormaterial along a boundary area, wherein the boundary area forms at leastone discrete multi-pointed enclosed shape when viewed from alongitudinal cross sectional view extending from the light input end tothe light output end, and wherein the boundary area extends from one endof a core width of the phase shifter to a second end of the core widthof the phase shifter.
 2. The phase shifter of claim 1, wherein the atleast one discrete multi-pointed shape comprises at least onemulti-pointed star.
 3. The phase shifter of claim 2, wherein the phaseshifter comprises a core height perpendicular to the core width of thephase shifter, wherein the boundary area extends from one end of thecore height of the phase shifter to a second end of the core height ofthe phase shifter.
 4. The phase shifter of claim 1, wherein the boundaryarea is greater than a length from the light input end to the lightoutput end multiplied by a core width of the phase shifter.
 5. The phaseshifter of claim 1, further comprising a core and a cladding, whereinthe core is part of a folded waveguide phase shifter in which light maypropagate through from the light input end to the light output end. 6.The phase shifter of claim 5, wherein the core is made of silicon andthe cladding is made of silicon oxide.
 7. The phase shifter of claim 5,wherein the core comprises a material selected from: silicon (Si),germanium (Ge), gallium arsenide (GaAs) and indium phosphide (InP). 8.The phase shifter of claim 5, wherein the cladding comprises a materialselected from: silicon oxide (SiOx), germanium oxide (GeOx), siliconnitride (SiNx) and silicon-oxynitride (SiON).
 9. A modulator,comprising: a first waveguide; and a second waveguide, comprising: alight input end, a light output end, a first semiconductor material, anda second semiconductor material different from the first semiconductormaterial, the second semiconductor material contacting the firstsemiconductor material along a boundary area, wherein a first lightoutput of the first waveguide is combined with a second light outputfrom the light output end, wherein the boundary area forms a pluralityof discrete multi-pointed enclosed shapes when viewed from alongitudinal cross sectional view extending from the light input end tothe light output end, wherein the first waveguide and the secondwaveguide are part of a processor.
 10. The modulator of claim 9, whereineach of the plurality of discrete multi-pointed shapes comprises amulti-pointed star.
 11. The modulator of claim 9, wherein the boundaryarea is greater than a length from the light input end to the lightoutput end multiplied by a core width of the second waveguide.
 12. Themodulator of claim 9, wherein the modulator comprises a Mach-Zehndermodulator that utilizes a folded waveguide phase shifter.
 13. Themodulator of claim 9, wherein the modulator comprises at least one oftwo arms optically coupled between cascaded Y-branch couplers disposedin a semiconductor material.
 14. A method, comprising: connecting afirst waveguide with a second waveguide different than the firstwaveguide, wherein the second waveguide comprises: a light input end, alight output end, a first semiconductor material, and a secondsemiconductor material, different from the first semiconductor material,the second semiconductor material contacting the first semiconductormaterial along a boundary area, wherein the boundary area forms aplurality of discrete multi-pointed enclosed shapes when viewed from alongitudinal cross sectional view extending from the light input end tothe light output end, and wherein the first waveguide and the secondwaveguide are part of a processor; and combining a first light output ofthe first waveguide with a second light output from the light outputend.
 15. The method of claim 14, comprising: connecting the light inputend to a first waveguide light input end.
 16. The method of claim 14,wherein each of the plurality of discrete multi-pointed shapes comprisesa multi-pointed star.
 17. The method of claim 14, wherein the boundaryarea is greater than a length from the light input end to the lightoutput end multiplied by a core width of the second waveguide.
 18. Themethod of claim 14, comprising: forming the boundary area from one endof the core width of the second waveguide to a second end of a corewidth of the second waveguide.
 19. The method of claim 14, comprising:connecting an input light source to the light input end.
 20. The methodof claim 19, wherein the boundary area is greater than a length from thelight input end to the light output end multiplied by a core width ofthe second waveguide.